My imported Cerbera still can't pass the Swedish mot...
Discussion
Hi everybody!
It was a while since I posted here, since then I've spent my time frustrated and angry (at times). Thing is, I've imported a -96 4.2 Cerbera to sweden. When trying to get it past the mot (early summer) everything went well except thet the exhaust readings (at idle) on the left bank were through the roof (HC = 1300ppm). Strangely enough, if you rev the engine up above 2000rpm the HC values fall below 40ppm (which is low enough). I was trying to fix this and managed to some degree.
This is what I've replaced:
- New plugs.
- New leads.
- New coils.
- New TPS (propperly set with the help of the diag. software)
- Big fuse checked
- New battery
This helped to some degree and I managed to get the HC readings down to 400ppm.
Recently, I've left it in the hands of some proffessionals (well, they havn't seen a TVR before) and they can't find what's wrong either. They checked all the sensors, measured compression, checked the cats and so on... (they also have access to the diag. software) they simply can't spot the problem.
They say that the left bank runs quite hot and every time they change someting that gets the exhaust values down below 100ppm, the system tryes to compensate back to around 400ppm (yes, adaptive maps was reset). I've read some posts about an engine rebuild manual, do you guys know where to get hold of it, might be good to check the valves/cams.
I simply don't know what else to do, does any of you have any ideas?
It was a while since I posted here, since then I've spent my time frustrated and angry (at times). Thing is, I've imported a -96 4.2 Cerbera to sweden. When trying to get it past the mot (early summer) everything went well except thet the exhaust readings (at idle) on the left bank were through the roof (HC = 1300ppm). Strangely enough, if you rev the engine up above 2000rpm the HC values fall below 40ppm (which is low enough). I was trying to fix this and managed to some degree.
This is what I've replaced:
- New plugs.
- New leads.
- New coils.
- New TPS (propperly set with the help of the diag. software)
- Big fuse checked
- New battery
This helped to some degree and I managed to get the HC readings down to 400ppm.
Recently, I've left it in the hands of some proffessionals (well, they havn't seen a TVR before) and they can't find what's wrong either. They checked all the sensors, measured compression, checked the cats and so on... (they also have access to the diag. software) they simply can't spot the problem.
They say that the left bank runs quite hot and every time they change someting that gets the exhaust values down below 100ppm, the system tryes to compensate back to around 400ppm (yes, adaptive maps was reset). I've read some posts about an engine rebuild manual, do you guys know where to get hold of it, might be good to check the valves/cams.
I simply don't know what else to do, does any of you have any ideas?
Reconnect the fuel regulator to the inlet manifold for the MOT.
In theory this should reduce the fuel pressure at 1500 - 2000 rpm. This will not improve overall emissions but should improve HC over that range.
Second, make sure you are in the car when the test is done. Foot on brake, and let the clutch slip ever so slightly while the test is done. Be very careful doing this.
Slightly loading the engine this way prevents the pops and bangs regularly heard on an idle revving Cerb. The pops and bangs are neat or partially burnt fuel in the exhaust. This is why loading the engine to stop them improves emissions.
Alternatively buy an after market ECU like emerald where you can have a special map for passing the mot and then switch back afterward. Or wait for developments on the MBE hopefully toward the start of next year.
In the UK we have a special rule for MOT's which states the car never has to be better than it left the factory. Which is why the Cerb is allowed to have an easier time through an MOT than most cars.
In theory this should reduce the fuel pressure at 1500 - 2000 rpm. This will not improve overall emissions but should improve HC over that range.
Second, make sure you are in the car when the test is done. Foot on brake, and let the clutch slip ever so slightly while the test is done. Be very careful doing this.
Slightly loading the engine this way prevents the pops and bangs regularly heard on an idle revving Cerb. The pops and bangs are neat or partially burnt fuel in the exhaust. This is why loading the engine to stop them improves emissions.
Alternatively buy an after market ECU like emerald where you can have a special map for passing the mot and then switch back afterward. Or wait for developments on the MBE hopefully toward the start of next year.
In the UK we have a special rule for MOT's which states the car never has to be better than it left the factory. Which is why the Cerb is allowed to have an easier time through an MOT than most cars.
Is it not as simple as setting up the throttle pots manually to compensate and then set them back to what is needed once its passed? Ignore the fact that they may not be set the same for both sides. As long as the outputs are correct for the emissions.
Adjust the throttle pots for that side and the fueling will change to what you require. Sometimes is that easy. I had large temp differences and everything looked fine on the laptop but this did the trick and the car ran even smoother in the end.
Give it a try!
Craig.
Adjust the throttle pots for that side and the fueling will change to what you require. Sometimes is that easy. I had large temp differences and everything looked fine on the laptop but this did the trick and the car ran even smoother in the end.
Give it a try!
Craig.
Zoltan said:
Thanks for all the advice guys!
julian64:
We have already reconnected the fuel pressure regulator, emmisions dropped and then rose again after a while. Sadly I can't usually be in the car while the test is done, it's done by guys at the mot station.
Not sure why that would be? Would have to scratch my head. The adaptives might have influenced the final figure after a while, but they are mainly used for adjusting bank to bank with the closed loop lambda which shouldn't have changed. Reconnecting the fuel regulator should have just dropped the amount the injectors can deliver across the range. Reset the adaptives and see if that makes the emissions jump down again for a while?julian64:
We have already reconnected the fuel pressure regulator, emmisions dropped and then rose again after a while. Sadly I can't usually be in the car while the test is done, it's done by guys at the mot station.
Sorry missed nitro's comment. He's absolutely right. The car only knows throttle position and revs as it doesn't measure intake air flow or manifold pressure. If you wind both throttle potentiometers to the point where the car is only just mainatining a tickover then you'll be on a less fuel part of the map at 1500-2000 rpm.
Also make sure if you can't sit in the car that you play with the throttle potentionmeters so that at the testing 1500-2000 each side of the engine is matched as well as possible and doesn't pop/bang.
This is a problem because while reducing your HC by reducing the fuel you will likely make the engine run less efficiently causing a certain rise in NO2. (Not that we test for that in this country)
Alternatively if you just can't get anything to work, it might be worth contacting jools at TCS and asking him if you can purchase a 'get you through the MOT' chip for your car. Its an easy quick plug in and then take out job, and its only an eprom.
Zoltan said:
oh... so there is a "get through mot" chip didn't know. I think I'll try with the chip then.
TCS? Is that Track Car Solutions?
didn't know. I think I'll try with the chip then.TCS? Is that Track Car Solutions?
http://www.track-car-solutions.co.uk/Gassing Station | Cerbera | Top of Page | What's New | My Stuff